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252 lines
8.3 KiB
C
252 lines
8.3 KiB
C
/* futex operations for glibc-internal use. Linux version.
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Copyright (C) 2014-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef FUTEX_INTERNAL_H
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#define FUTEX_INTERNAL_H
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#include <sysdeps/nptl/futex-internal.h>
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#include <errno.h>
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#include <lowlevellock-futex.h>
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#include <nptl/pthreadP.h>
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/* See sysdeps/nptl/futex-internal.h for documentation; this file only
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contains Linux-specific comments.
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The Linux kernel treats provides absolute timeouts based on the
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CLOCK_REALTIME clock and relative timeouts measured against the
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CLOCK_MONOTONIC clock.
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We expect a Linux kernel version of 2.6.22 or more recent (since this
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version, EINTR is not returned on spurious wake-ups anymore). */
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/* FUTEX_SHARED is always supported by the Linux kernel. */
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static __always_inline int
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futex_supports_pshared (int pshared)
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{
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if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
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return 0;
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else if (pshared == PTHREAD_PROCESS_SHARED)
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return 0;
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else
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return EINVAL;
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}
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/* The Linux kernel supports relative timeouts measured against the
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CLOCK_MONOTONIC clock. */
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static __always_inline bool
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futex_supports_exact_relative_timeouts (void)
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{
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return true;
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline int
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futex_wait (unsigned int *futex_word, unsigned int expected, int private)
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{
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int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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return -err;
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case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -EINVAL: /* Either due to wrong alignment or due to the timeout not
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being normalized. Must have been caused by a glibc or
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application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline int
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futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
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int private)
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{
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int oldtype;
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oldtype = __pthread_enable_asynccancel ();
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int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
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__pthread_disable_asynccancel (oldtype);
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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return -err;
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case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -EINVAL: /* Either due to wrong alignment or due to the timeout not
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being normalized. Must have been caused by a glibc or
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application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline int
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futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
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const struct timespec *reltime, int private)
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{
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int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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case -ETIMEDOUT:
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return -err;
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -EINVAL: /* Either due to wrong alignment or due to the timeout not
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being normalized. Must have been caused by a glibc or
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application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline int
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futex_reltimed_wait_cancelable (unsigned int *futex_word,
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unsigned int expected,
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const struct timespec *reltime, int private)
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{
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int oldtype;
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oldtype = __pthread_enable_asynccancel ();
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int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
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__pthread_disable_asynccancel (oldtype);
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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case -ETIMEDOUT:
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return -err;
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -EINVAL: /* Either due to wrong alignment or due to the timeout not
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being normalized. Must have been caused by a glibc or
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application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline int
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futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
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const struct timespec *abstime, int private)
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{
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/* Work around the fact that the kernel rejects negative timeout values
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despite them being valid. */
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if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
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return ETIMEDOUT;
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int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,
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FUTEX_CLOCK_REALTIME, private);
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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case -ETIMEDOUT:
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return -err;
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -EINVAL: /* Either due to wrong alignment or due to the timeout not
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being normalized. Must have been caused by a glibc or
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application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline int
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futex_abstimed_wait_cancelable (unsigned int *futex_word,
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unsigned int expected,
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const struct timespec *abstime, int private)
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{
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/* Work around the fact that the kernel rejects negative timeout values
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despite them being valid. */
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if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
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return ETIMEDOUT;
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int oldtype;
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oldtype = __pthread_enable_asynccancel ();
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int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,
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FUTEX_CLOCK_REALTIME, private);
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__pthread_disable_asynccancel (oldtype);
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switch (err)
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{
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case 0:
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case -EAGAIN:
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case -EINTR:
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case -ETIMEDOUT:
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return -err;
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case -EFAULT: /* Must have been caused by a glibc or application bug. */
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case -EINVAL: /* Either due to wrong alignment or due to the timeout not
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being normalized. Must have been caused by a glibc or
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application bug. */
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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/* See sysdeps/nptl/futex-internal.h for details. */
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static __always_inline void
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futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
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{
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int res = lll_futex_wake (futex_word, processes_to_wake, private);
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/* No error. Ignore the number of woken processes. */
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if (res >= 0)
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return;
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switch (res)
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{
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case -EFAULT: /* Could have happened due to memory reuse. */
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case -EINVAL: /* Could be either due to incorrect alignment (a bug in
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glibc or in the application) or due to memory being
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reused for a PI futex. We cannot distinguish between the
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two causes, and one of them is correct use, so we do not
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act in this case. */
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return;
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case -ENOSYS: /* Must have been caused by a glibc bug. */
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/* No other errors are documented at this time. */
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default:
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futex_fatal_error ();
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}
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}
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#endif /* futex-internal.h */
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